Coal, which is primarily carbon, can be converted to natural gas, primarily ch4, by the exothermic reaction:

Unfortunately, your question is incomplete So, according to the attached picture of the complete question we will explain the
according to the reaction equation:
C(s) + 2H2(g) ↔ CH4(g) ΔH° = -74.6KJ 
So the true answer will be D i and ii

- as by adding more C and it is a reactant so the reaction will go rightward to the product to decrease the C to achieve the equilibrium again, the movement of the reaction towards the products will make the CH4 increase

- and by decreasing the Heat and the heat here is as a product as the reaction is exothermic so by decreasing the heat the reaction will go toward the products to increase the heat and achieve the equilibrium again, and that also makes the CH4 increase as it is a product.
So the true answer is D i and ii as the attached photo